As a transfusion blood bag vessel, there have been used vessels obtained by forming a film of polyvinyl chloride, polyethylene, polypropylene or the like into the shape of a sack. In general, medicinal liquids such as an anticoagulant solution and a red cell storage solution which are contained in blood bags are often discolored or altered due to oxygen in the air. In addition, since the amounts of the medicinal liquids contained in blood bags are small, the medicinal liquids are susceptible to the influence of concentration variations due to transpiration of water. In order to suppress these phenomena, blood bags are packaged with a packaging material which is excellent in gas barrier properties (water vapor and oxygen barrier properties).
There have been proposed methods in which various gas barrier laminate films are used as a packaging material excellent in gas barrier properties for use in a blood bag. Examples of such packaging material include: a double packaging sack (double packaging material) wherein a polyethylene or polypropylene film is used as an inner packaging material, and a laminate film such as a polyethylene/aluminum foil/polyamide laminate film is used as an outer packaging material, such as described in Japanese Patent Laid-open No. Hei 8-243148; and a double packaging sack (double packaging material) wherein a laminate film having a laminate structure of low-density polyethylene/silica-deposited biaxially oriented polyethylene terephthalate film (deposited PET)/biaxially oriented polyamide film (ONy)/linear low-density polyethylene (LLDPE) film is used as an inner packaging material, and a laminate film having a laminate structure of biaxially oriented polyamide film (ONy)/linear low-density polyethylene (LLDPE) film is used as an outer packaging material such as described in Japanese Patent Laid-open No. 2009-143571.
In addition, as a laminate having transparency and better gas barrier properties, there have been proposed laminates having a structure wherein a laminate film obtained by laminating two laminate films each having a laminate structure of PET/vapor-deposited aluminum oxide film/sol-gel process type barrier coat/vapor-deposited aluminum oxide film/sol-gel process type barrier coat, with the sol-gel process type barrier coat surfaces on the inside, by use of a dry laminate adhesive or the like is laminated with a sol-gel process type barrier coat/CVD-deposited silicon oxide film/ONy and an LLDEP film by use of a dry laminate adhesive or the like, an example of such laminates being a laminate having a laminate structure of PET/vapor-deposited aluminum oxide film/sol-gel process type barrier coat/vapor-deposited aluminum oxide film/sol-gel process type barrier coat/adhesive/sol-gel process type barrier coat/vapor-deposited aluminum oxide film/sol-gel process type barrier coat/vapor-deposited aluminum oxide film/PET/adhesive/sol-gel process type barrier coat/CVD-deposited silicon oxide film/ONy/adhesive/LLDPE film such as described in Japanese Patent Laid-open No. 2009-248455.
However, the gas barrier packaging material proposed in Japanese Patent Laid-open No. Hei 8-243148 and the like is opaque due to the use of the aluminum foil, and the packaging material proposed in Japanese Patent Laid-open No. 2009-143571 and the like having the deposited PET film is essentially a double packaging material, though it has transparency. On the other hand, the laminate proposed in Japanese Patent Laid-open No. 2009-248455 and the like may require a complicated production process as represented for example by the need to perform vapor deposition twice, although it has excellent transparency and excellent gas barrier properties.